The services are very tightly targeted by age. The first six include maths and english for five- to seven-year-olds, science for seven to nines, geography for seven to 11s, French for 11- to 14-year-olds and business studies for 14-16.

They can be accessed by dial-up internet, though they work best on broadband because of the animation and games they include. The government's aim is for all schools to have broadband connections by the end of this year, up from around 80% last year.

The BBC expects to add 14 more sites in 2006, ranging from science and geography to statistics and financial capability (for 14- to 16-year-olds), with field studies for learners with severe difficulties.

The launch is intentionally low-key until the BBC quiets the controversy and concerns the sites have created.

The deceptively low-key and limited start - there will be no proper marketing until September - is deliberate. The embryonic service has already been criticised by the content advisory board monitoring the service on behalf of the government, which says it is not meeting tough conditions to differentiate it from commercial publishing material.

The corporation says it is puzzled by this: "We urge people to go online and form their own views." The BBC team is confident it has something special on its hands, but it intends to work closely with teachers and users to see whether adjustments are needed.